Safety factor, temperature and torque

In summary, the hub has a safety factor of against yielding with a sum of resisting moments/sum of driving moments of (moment on shaft face + moment by contact pressure)/torque.
  • #1
r_prieto5
18
0

Homework Statement



https://drive.google.com/file/d/0BxPEJS0qVOpeWENSREI1RlNsNDQ/view?usp=sharing

A hub is connected to a shaft with a shrink fit (pressurized oil assembly, grease removed). The material of the hub is quenched and tempered steel (ReH = 450 N/mm2) and the material of the shaft is steel S355. The diameter DF = 30 mm and the length of the D sleeve is l = 30 mm. The outside diameter of the hub is D = 140 mm. Interference fit is

φ30H7/u6 . Surface roughnesses of the shaft and the hub are according to SFS 5595. The

load is pulsating: T = 150 Nm and Fa = 9000 N.

  1. a) Calculate the safety factor against sliding.
  2. b) Calculate the safety factor of the hub against the yielding.
  3. c) Calculate the temperature of the hub at assembly.
  4. d) Calculate the transmitted torque, if a parallel key (SFS 2636) is used to connect the

    hub to the shaft. The key length is 30 mm.

Homework Equations


Maybe from a similar problem and only for d)

T = (π/2)⋅DF2⋅lF⋅vru(p/Sr)

The Attempt at a Solution


Sadly, as with my other homework problems, I do not have any formulas or methods showing me how to solve it since the course material is in Finnish.
I can't use the Torque formula either since I don't yet have the safety factors...
 
Last edited by a moderator:
Physics news on Phys.org
  • #2
  • Like
Likes r_prieto5 and mfb
  • #3
@Nidum Thank you, I am pretty busy at the moment but I will get more into it next week and let you know if it works!
 
  • #4
@Nidum It seems the links you give me don't have much information on the actual values asked and if they do, they require that I already have calculated some of the other variables (i.e. the calculator). Do you have any information on how I should start the approach?
 
  • #5
To answer all the main parts of the original question you first need to evaluate :

(a) the interface stress between the shaft and the ring .
(b) the coefficient of friction effective between the shaft and the ring .

There is a range of possible values for each of these quantities .
Decide for yourself which are the safest values to use in further calculations .
 
  • #6
Ok, I think I have now found the safety factor against sliding with sum of resisting moments/sum of driving moments = (moment on shaft face + moment by contact pressure)/torque
Now for the yielding safety factor i found the formula FS=yield strength (of the shaft i guess)/von mises maximum stress however I don't know how to find von mises' maximum stress...
 

Related to Safety factor, temperature and torque

1. What is a safety factor and why is it important in engineering?

A safety factor is a measure of how much stronger a material or structure is compared to what is required for its intended use. It is important in engineering because it ensures that the design can withstand unexpected loads or stresses without failure, providing a margin of safety for the intended use.

2. How does temperature affect the safety factor of a material?

Temperature can have a significant impact on the safety factor of a material. As temperature increases, the strength and stiffness of most materials decrease, reducing their ability to withstand stress and increasing the risk of failure. This is especially important to consider in applications where temperature fluctuations are expected.

3. What is the relationship between torque and safety factor?

Torque is a measure of the rotational force applied to an object. In engineering, the safety factor for torque refers to the ratio of the maximum torque that a component is expected to experience to the maximum torque it can withstand before failure. A higher safety factor for torque means that the component can handle higher levels of torque without failing.

4. How can the safety factor for torque be calculated?

The safety factor for torque can be calculated by dividing the maximum torque that a component is expected to experience by the maximum torque it can withstand before failure. For example, if a component is expected to experience a maximum torque of 500 N-m and can withstand a maximum torque of 1000 N-m, the safety factor would be 1000/500 = 2.

5. How does the safety factor for temperature and torque affect the overall safety of a design?

The safety factor for temperature and torque is an important consideration in ensuring the overall safety of a design. If the safety factor is too low, the design may be at risk of failure under normal operating conditions. However, a higher safety factor does not necessarily mean a design is safer, as it may also result in unnecessary material and manufacturing costs. A balance between safety and efficiency must be achieved in the design process.

Similar threads

How Do You Calculate Deflection and Shear Stress in a Tapered Shaft?
    • Mechanical Engineering
Replies
2
Views
2K
Factor of Safety - Mechanics of Materials
    • Engineering and Comp Sci Homework Help
Replies
4
Views
5K
Calculating direct stress safety factor
    • Engineering and Comp Sci Homework Help
Replies
2
Views
29K
Torque calculations: Rotating vertical shaft
    • Mechanical Engineering
Replies
5
Views
3K
Strength of material in hollow shaft torque and safety factor
    • Engineering and Comp Sci Homework Help
Replies
5
Views
5K
How much should I adjust torque when using anti-seize?
    • Mechanical Engineering
Replies
21
Views
811
Torque Transmission - Slippage at Press Fit Connection
    • Mechanical Engineering
Replies
11
Views
16K
Radial Deflection of a rotating shaft
    • Engineering and Comp Sci Homework Help
Replies
11
Views
4K
Help with Factor Of Safety (FOS) in Bolt Shear problem
    • Introductory Physics Homework Help
Replies
29
Views
4K
Total moment caused by an unbalanced mass on a rotating shaft
    • Engineering and Comp Sci Homework Help
Replies
5
Views
3K

Hot Threads

Recent Insights

Back
Top